Carbon monoxide gas is poisonous in high concentrations. However, it is now recognized as an important signaling molecule (Verma et al., Science 259:381-384, 1993). It has also been suggested that carbon monoxide acts as a neuronal messenger molecule in the brain (Id.) and as a neuro-endocrine modulator in the hypothalamus (Pozzoli et al., Endocrinology 735:2314-2317, 1994). Like nitric oxide (NO), carbon monoxide is a smooth muscle relaxant (Utz et al., Biochem Pharmacol. 47:195-201, 1991; Christodoulides et al., Circulation 97:2306-9, 1995) and inhibits platelet aggregation (Mansouri et al., Thromb Haemost. 48:286-8, 1982). Inhalation of low levels of carbon monoxide (CO) has been shown to have anti-inflammatory effects in some models.
Hepatitis is a disease characterized by inflammation of the liver. The inflammation can be characterized by diffuse or patchy necrosis affecting acini. Causative agents of hepatitis include, for example, viruses, e.g., specific hepatitis viruses, e.g., hepatitis A, B, C, D, E, and G viruses; alcohol; and other drugs (e.g., isoniazid, methyldopa, acetaminophen, amiodarone, and nitrofurantoin) (see The Merck Manual of Diagnosis and Therapy, 17th Edition, Section 4, Chapter 42).